Art of mounting piezoelectric crystals



F. W. LUTZENS zxmms ART OF MOUNTING PIEZOELECTRIG CRYSTALS Filed Nov. 29, 1941 teeters or area emaoerare l W, ilnduh it. i near a a mention at it invention relates to the art oi moms pieseeleetrie erystal elents has special reierence to the provision oi improvements in nodal mounting a r iernents oi the type wherein the electrodes tor the oral are in the to at separate rent conductive coatings or metahleeti s.

"lilie principal ohiect oi the invention is to provide a reliahle yet irpensive mount for plated crystals and one which may be made irotn readily ohtainahle materials without the use of dies or other special tools. I

it related ohject oi the invention is to provide novel and compact sup for a plated crystal, and one which dispenses with the necessity of soldered or other aunillary electrical connectors tor -lilre metal electrodes.

another ohieet oi the present invtion in We provide an improved crystal-mount cble at aeeornmodating erys oi diderent sizes, and one adapted with hot minor changes to the at either a thlcmess-rnode or a contain-anode crystal.

tithes ohieeta and advantages, together with in pretemed details oi construction, will he rent and the invention itseli will be best it tier-stood hy reference to the iollowing speclfi ration and to the accompanying drawing, wherein l is a side elevational view and Fig. 2 a top plan oi a plated contour-mode crystal lilflllll'ie di in accordance with the invention.

li ig. i is side elevational view oi an alte r it tive embodiment oi the invention,

d is a iragmentary side elevations] view oi another ensoodent oi the invention,

Fig. ii is a side elevational view of a mount within the invention adapted ior use with a soeallerl Went thielmess-mode crystal, and

d is a oross-sectional view talren on the line at Fig. 2.

in the drawing. wherein lilre reierencev characters designate the same or corresponding parts in all Q designates a quarts or other crystal element having piezoelectric properties. til'ontiguous the opposite major iaces oi the crystal Q are electrodes E1 and E2, respectively, which preierahiy comprise integral or adherent coatings iorrned oi evaporated metal, or metal loll.

in accordance with the invention, the crystal til supported lay two wires W1 and W2, u tively, which are so bent, spliced, insulated-and tensioned, as to comprise a loop L within which the crystal is clamped.

en, a can at r E9, ran, rial No. esters (or. Jill-d2?) W W1 and We also serve as conductive leads for app the appropriate potentials to the crystal through its electrodes E1 and E2. In

order to prevent short-circuiting between the oosite electrodes, the tree ends of the le Wx and W2 are provided with insulating terminals t1 and is. as shown in Figures 1, 2 and 5, these te i may comprise simply an insulated section oi the wire wound tightly about that ated or noninsulated part of the other wire which lies adjacent the opposite edge of the crystal. Alternatively, the free ends of each wire W may have a slidahle ht with respect to the other. Thus, as shown in re 3, the free end of each lead wire W may terminate in a small loop 01, respectively, or, referring to Fl 4,

each wire be secured to insulating grommet n which is slldably fitted about the other wire of the pair.

Where, as in the embodiments oi the invention shown in l to i inclusive the crystal Q is oi the low irequency ype and has a nodal axis which extends thereacross, the conductive leads or wirw W1 and W: are arranged to contact the opposite plated surfaces E1 and E2 in register with the said nodal axis, in order to minimize damping eiiiects. On the other hand; where, as shown in Figure 5, the crystal comprises a socalled "thickness-mode, high frequency crystal. the wires W1 and We are preferably bent or bowed outwardly away from, and out of contact with, the central areas 01! the electrodes E1 and E2 so that the clamp force is confined to the end zones oi the crystal. As shown more clearly in Figure 6, the surface portions of the wires which contact the electrode laces E1 and E: are preferably flattened as indicated at! and may he owned to the said faces by an application of a silver cement or other electrically conductive adhesive. Alternatively, as indicated in Figure ii, the wires W1 and a may be maintained in position by mating them within grooves o provided for the purpose adjacent its opposite edges or on the tor surfaces of the crystal.

Various other embodiments of the invention will suggest themselves to those skilled in the art. It is to be understood, therefore, that the foregoing is to be interpreted as illustrative and not in a limiting sense except as required by the spirit of the appended claims.

What is claimed is:

l. In combination, a piesoelectric l ment having a pair of oppositely located metalectrode faces and a loop in which said :1 is mounted. said loop comprising a of conductive leads insulatingly connected at opposite sides of said crystal and each electrically connected intermediate its ends with one of said metallized electrode faces.

2. In combination, a piezoelectric crystal element having a pair of adherent electrodes on its opposite major faces, a conductive lead extending across said crystal in contact with one of said electrodes, a second conductive lead extending across said crystal in contact with the other of said electrodes, and insulating means on said leads adjacent opposite sides of said crystal for applying a mounting force to said crystal through said conductive leads.

3. The invention as set forth in claim 2 wherein said piezoelectric crystal comprises a quartz element of the type having a nodal axis which extends thereacross and wherein said conductive leads are arranged in ter with said nodal axis.

4:. The invention as set forth in claim 2 wherein said piezoelectric crystal comprises a quartz element of the type having opposite end zones of minimum piezoelectric activity and wherein the mounting force exerted through said conductive leads is applied to said element adjacent said end zones.

5. The invention as set forth in claim 2 and wherein said insulating means comprises a ringlike element mounted on the free end of each lead and through which the other of said leads extends.

6. The invention as set forth in claim 2 and wherein those parts of said leads which lie contiguous said electrodes comprise plane surfaces.

'7. The invention as set forth in claim 2 and wherein a surface of said crystal is provided with a groove in which said lead is seated.

FREDRICH W. LU'IZENS. 

